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devbox.json Reference

Your devbox configuration is stored in a devbox.json file, located in your project's root directory. This file can be edited directly, or using the devbox CLI.

{
    "packages": [] | {},
    "env": {},
    "shell": {
        "init_hook": "...",
        "scripts": {}
    },
    "include": []
}

Packages​

This is a list or map of Nix packages that should be installed in your Devbox shell and containers. These packages will only be installed and available within your shell, and will have precedence over any packages installed in your local machine. You can search for Nix packages using Nix Package Search.

You can add packages to your devbox.json using devbox add <package_name>, and remove them using devbox rm <package_name>.

Packages can be structured as a list of package names (<packages>@<version>) or flake references:

{
    "packages": [
        "go@latest",
        "golangci-lint@latest"
    ]
}

If you need to provide more options to your packages (such as limiting which platforms will install the package), you can structure packages as a map, where each package follows the schema below:

{
    "packages": {
        // If only a version is specified, you can abbreviate the maps as "package_name": "version"
        "package_name": string,
        "package_name": {
            // Version of the package to install. Defaults to "latest"
            "version": string,
            // Whether native library patching is enabled for this package. This defaults to `auto`, but can be overridden to `always` or `never` for individual packages.
            "patch": ["auto" | "always" | "never"],
            // List of platforms to install the package on. Defaults to all platforms
            "platforms": [string],
            // List of platforms to exclude this package from. Defaults to no excluded platforms
            "excluded_platforms": [string],
            // Whether to disable a built-in plugin, if one exists for this package. Defaults to false
            "disable_plugin": boolean
        }
    }
}

For example:

{
    "packages": {
        "go" : "latest",
        "golangci-lint": "latest",
        "glibcLocales": {
            "version": "latest",
            "platforms": ["x86_64-linux, aarch64-linux"]
        }
    }
}

Note that devbox add will automatically format packages based on the options and packages that you provide.

Pinning a Specific Version of a Package​

You can pin a specific version of a package by adding a @ followed by the version number to the end of the package name. For example, to pin the go package to version 1.19, you can run devbox add go@1.19, or add go@1.19 to the packages list in your devbox.json:

{
    "packages": [
        "go@1.19"
    ]
}

Where possible, pinned packages follow semver. For example, if you pin python@3, it will install the latest version of python with major version 3.

To see a list of packages and their available versions, you can run devbox search <pkg>.

Adding Packages from Flakes​

You can add packages from flakes by adding a reference to the flake in the packages list in your devbox.json. We currently support installing Flakes from Github and local paths.

{
    "packages": [
        // Add the default package from a github repository
        "github:numtide/flake-utils",
        // Install a specific attribute or package from a Github hosted flake
        "github:nix-community/fenix#stable.toolchain",
        // Install a package from a specific channel of Nixpkgs
        "github:nixos/nixpkgs/21.05#hello",
        // Install a package form a specific commit of Nixpkgs
        "github:nixos/nixpkgs/5233fd2ba76a3accb5aaa999c00509a11fd0793c#hello",
        // Install a package from a local flake. This should point to a directory that contains a flake.nix file.
        "path:../my-flake#my-package"
    ]
}

To learn more about using flakes, see the Using Flakes guide.

Adding Platform Specific Packages​

You can choose to include or exclude your packages on specific platforms by adding a platforms or excluded_platforms field to your package definition. This is useful if you need to install packages or libraries that are only available on specific platforms (such as busybox on Linux, or utm on macOS):

{
    "packages": {
        // Only install busybox on linux
        "busybox": {
            "version": "latest",
            "platforms": ["x86_64-linux", "aarch64-linux"]
        },
        // Exclude UTM on Linux
        "utm": {
            "version": "latest",
            "excluded_platforms": ["x86_64-linux", "aarch64-linux"]
        }
    }
}

Note that a package can only specify one of platforms or excluded_platforms.

Valid Platforms include:

  • aarch64-darwin
  • aarch64-linux
  • x86_64-darwin
  • x86_64-linux

The platforms below are also supported, but require you to build packages from source:

  • i686-linux
  • armv7l-linux

Disabling Built-in Plugins​

Some packages include builtin plugins or services that are automatically started when the package is installed. You can disable these plugins using devbox add <package> --disable-plugin, or by setting the disable_plugin field to true in your package definition:

{
    "packages": {
        "glibcLocales": {
            "version": "latest",
            "disable_plugin": true
        }
    }
}

Env​

This is a a map of key-value pairs that should be set as Environment Variables when activating devbox shell, running a script with devbox run, or starting a service. These variables will only be set in your Devbox shell, and will have precedence over any environment variables set in your local machine or by Devbox Plugins.

For example, you could set variable $FOO to bar by adding the following to your devbox.json:

{
    "env": {
        "FOO": "bar"
    }
}

Currently, you can only set values using string literals, $PWD, and $PATH. Any other values with environment variables will not be expanded when starting your shell.

Env From​

Env from takes a string or list of strings for loading environment variables into your shells and scripts. Currently it supports loading from two sources: .env files, and Jetify Secrsts.

.env Files​

You can load environment variables from a .env file by adding the path to the file in the env_from field. This is useful for loading secrets or other sensitive information that you don't want to store in your devbox.json.

{
    "env_from": "path/to/.env"
}

This will load the environment variables from the .env file into your shell when you run devbox shell or devbox run. Note that environment variables set in the .env file will be overridden if the same variable is set directly in your devbox.json

Jetify Secrets​

You can securely load secrets from Jetify Secrets by running devbox secrets init and creating a project in Jetify Cloud. This will add the jetpack-cloud field to env_from in your project.

{
    "env_from": "jetpack-cloud"
}

Note that setting secrets securetly with Jetify Secrets requires a Jetify Cloud account. For more information, see the Jetify Secrets guide.

Shell​

The Shell object defines init hooks and scripts that can be run with your shell. Right now two fields are supported: init_hook, which run a set of commands every time you start a devbox shell, and scripts, which are commands that can be run using devbox run

Init Hook​

The init hook is used to run shell commands before the shell finishes setting up. This hook runs after any other ~/.*rc scripts, allowing you to override environment variables or further customize the shell.

The init hook will run every time a new shell is started using devbox shell or devbox run, and is best used for setting up environment variables, aliases, or other quick setup steps needed to configure your environment. For longer running tasks, you should consider using a Script.

This is an example devbox.json that customizes the prompt and prints a welcome message:

{
    "shell": {
        "init_hook": [
            "export PS1='📦 devbox> '",
            "echo 'Welcome! See CONTRIBUTING.md for tips on contributing to devbox.'"
        ]
    }
}

When run, you'll see:

> devbox shell
Installing nix packages. This may take a while...
Starting a devbox shell...
Welcome! See CONTRIBUTING.md for tips on contributing to devbox.
📦 devbox>

Scripts​

Scripts are commands that are executed in your Devbox shell using devbox run <script_name>. They can be used to start up background process (like databases or servers), or to run one off commands (like setting up a dev DB, or running your tests).

Scripts can be defined by giving a name, and one or more commands. Single command scripts can be added by providing a name, and a string:

{
    "shell": {
        "scripts": {
            "print_once": "echo \"Hello Once!\""
        }
    }
}

To run multiple commands in a single script, you can pass them as an array:

{
    "shell": {
        "scripts": {
            "print_twice": [
                "echo \"Hello Once!\"",
                "echo \"Hello Twice!\""
            ]
        }
    }
}

Include​

Includes can be used to explicitly add extra configuration from plugins to your Devbox project. Plugins are parsed and merged in the order they are listed.

Note that in the event of a conflict, plugins near the end of the list will override plugins at the beginning of the list. Likewise, if a setting in your project config conflicts with a plugin (e.g., your devbox.json has a script with the same name as a plugin script), your project config will take precedence.

{
    "include": [
        // Include a plugin from a Github Repo. The repo must have a plugin.json in it's root,
        // or in the directory specified by ?dir
        "github:org/repo/ref?dir=<path-to-plugin>"
        // Include a local plugin. The path must point to a plugin.json
        "path:path/to/plugin.json"
        // Force activate a builtin plugin
        "plugin:php-config"
    ]
}

Example: A Rust Devbox​

An example of a devbox configuration for a Rust project called hello_world might look like the following:

{
    "packages": [
        "rustup@latest",
        "libiconv@latest"
    ],
    "env": {
        "PROJECT_DIR": "$PWD"
    },
    "shell": {
        "init_hook": [
            ". conf/set-env.sh",
            "rustup default stable",
            "cargo fetch"
        ],
        "scripts": {
            "build-docs": "cargo doc",
            "start": "cargo run",
            "run_test": [
                "cargo test -- --show-output"
            ]
        }
    }
}